1. Field of the Invention
The present invention relates to pipe connectors for connecting pipes particularly but not exclusively for use in conveying pressurized fluids, for example steam, gas or oil, for example in oil or gas exploration or production.
2. Description of the Prior Art
One of the main types of connector presently used for such purposes comprises a female member having an internal circumferential surface provided with a thread and a male member having a corresponding external circumferential surface also provided with a thread which is threadedly received within the female member. Seals are required between the members and frequently one such seal is provided by abutment between an axially facing surface on the free end of one of the members, generally the male member, and a corresponding surface provided on the other member, the surfaces being abutted under compression when the members are fully engaged together. To obtain seals which will withstand conditions of use, the surfaces need to be abutted under triaxial compression, i.e. compressive forces in axial, radial and circumferential directions. To obtain this the abutted surfaces are directed radially as well as axially. In one connector the free end of the male member is provided with two oppositely directed frusto-conical surfaces being a radially outer surface the apex of the cone of which is directed outwardly of the male member and a radially inner surface the apex of the cone of which is directed inwardly of the member, such that the free end of the male member has a generally V-shaped section in a radial plane. Corresponding surfaces are provided on a shoulder in the female member and the two members are relatively dimensioned so that the radially inner surface on the male member comes into contact with the corresponding surface on the female member first and is then deformed to bring the radially outer surface on the male member into contact with the corresponding surface on the female member. However in this connector, when the two members are fully engaged together, a very high stress concentration may occur along the line joining the two frusto-conical surfaces of the male member and this can cause part of the shoulder of the female member extending from this line of high stress concentration to shear off, totally destroying the seal.